1. Field of Invention
The present invention relates to a level-shift circuit, and more particularly to a system status display module and a level-shift circuit thereof that transforms the different voltage ranges of plural system status signals.
2. Related Art
The status data of computer system allows a engineer to know the current status of the BIOS (Basic Input/Output System), the CPU (Central Processing Unit), the system memory, the operation of the mother board, the power supply, the input/output devices and the peripherals. Generally, a signal cable is used to output various system status signals from the mother board to a system status display module, such as a LCD (Liquid Crystal Display) to display the system status.
In the prior art, the mother boards usually have different designs for the signal sources and transmission paths of the system status data. What more complex is that the system status signals have different operating voltage ranges. If the signal status signals have different voltage ranges from the operating voltage of the display controller of the system status display module, the display will possibly make error identifications on the logic high/low of the system status signals, and thereby displaying the wrong data. For example, a system status signal S1 sourced from a South Bridge or an I/O controller (such as a Super I/O controller) has a voltage range of 0˜5 V, while another system status signal S2 transmitted through a COM port (communication port) controller has a raised voltage range of −12˜12V. Then, if a display controller of the system status display module has an operating voltage range of 0˜5 V, the display controller will possibly read and display the −12˜12V system status signal S2 in a totally opposite way. Actually, even the signal source is the same, inappropriate voltage ranges of the system status signals lead to different reading results.
However, there is no appropriate solution that can be applied to different mother boards for displaying system status, or allow the system status display module to read and display the system status signals with different voltage ranges from different mother boards or different system components.